Effects of feed pretreatment on PRO performance: Brief review and experimental investigation

Pressure retarded osmosis (PRO) is a promising renewable energy technology that harnesses energy from the osmotic pressure difference. PRO offers a stable, continuous energy supply that is independent of climatic conditions and can also address brine disposal from desalination plants by utilizing it as a draw solution. However, membrane fouling and concentration polarization, induced by contaminants in the feed solution, significantly decrease its energy efficiency during operation. This study investigates the impact of microfiltration (MF) pretreatment on the energy production efficiency of PRO processes using secondary wastewater effluent and river water as feed solutions. It also includes a literature review of recent advancements in PRO for energy recovery. This study evaluated the changes in PRO power density following MF pretreatment. Secondary wastewater effluent and river water were used as representative feed waters to demonstrate the influence of water quality management on PRO energy recovery. The results demonstrated substantial improvement in performance, with an approximate 80% increase in maximum power density after pretreatment of secondary wastewater effluent, whereas only marginal improvements were observed for river water. These findings indicate that pretreatment effectiveness varies with the characteristics of organic and particulate matter in feed solutions, indicating the need for tailored pretreatment strategies.